Li Jia, Deng Xiaojiao, Zheng Xiaoping, Li Li, Ren Yimin
Department of Automation, Tsinghua University, Beijing, 100084, China.
Department of Automation, Tsinghua University, Beijing, 100084, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Aug 5;276:121208. doi: 10.1016/j.saa.2022.121208. Epub 2022 Mar 30.
Quantitative analysis of trace gases is an important research field in analytical chemistry. The terahertz electronic spectrometer is one of the most powerful tools for detecting trace gas. Here, a terahertz spectrometer based on frequency multiplier chain and heterodyne detection was presented. The rotational spectra of acetonitrile (CHCN) gas were measured in the 290-370 GHz frequency band with 100 kHz spectral resolution. The spectrometer demonstrated excellent spectral specificity and the extrapolated limit of detection for CHCN gas of 1.4 ppm. Furthermore, a novel quantification method of trace gas was proposed based on broadening mechanisms. The CHCN self- and nitrogen (N)- collisional broadening coefficients were obtained experimentally for verifying the method. The CHCN concentration of the validation group was calculated, and the relative error was 0.1%. The error analysis of the different number of measurements of the method was carried out. The method could provide a new perspective for trace gas quantitative analysis.
痕量气体的定量分析是分析化学中的一个重要研究领域。太赫兹电子光谱仪是检测痕量气体最强大的工具之一。在此，介绍了一种基于倍频链和外差检测的太赫兹光谱仪。在290 - 370 GHz频段以100 kHz的光谱分辨率测量了乙腈（CHCN）气体的转动光谱。该光谱仪表现出优异的光谱特异性，CHCN气体的外推检测限为1.4 ppm。此外，基于展宽机制提出了一种痕量气体的新型定量方法。通过实验获得了CHCN自身和氮气（N）的碰撞展宽系数以验证该方法。计算了验证组的CHCN浓度，相对误差为0.1%。对该方法不同测量次数进行了误差分析。该方法可为痕量气体定量分析提供新的视角。
